SC&A Status Update – Evaluation of 

Areas and Times that NIOSH has 

Determined Doses are 

Reconstructable

John Stiver

S. Cohen and Associates

Contractor to:

Advisory Board on Radiation and Worker Health/ABRWH

Centers For Disease Control and Prevention

July 8, 2015
Introduction and Background

• Due to the complexity of INL, the Board determined that its review of 

the ER should be performed in a graded manner, whereby SC&A would 

first conduct a preliminary review of certain issues of most immediate 

concern to the Board.

• SC&A near-term tasking to support the July 8, 2015, WG meeting and 

the July 23, 2015, Board session: 

• Evaluate the proposed class definition and also begin a focused evaluation 

of the areas, activities and times for which NIOSH has determined that 

doses are reconstructable with sufficient accuracy

• This review, in addition to being preliminary due to time constraints, is 

also very much a work in progress. 

• This presentation is strictly to inform and recommend areas where we 

believe more research/investigation is needed. No judgments or 

conclusions are being drawn at this preliminary stage.

2
Introduction and Background (cont’d)

Dose Reconstructability/Gap Analysis

• Approach: “Horizontal” and “Vertical” analysis

• Horizontal – examine the DR methodology applied by 

NIOSH for all INL personnel – cross cutting

• Vertical – specific characteristics of the individual areas at 

the INL site

• 6 areas of investigation:

1. Fission and Activation Product (FAP) Bioassay Indicator 

Radionuclides (horizontal)

2. Reactor Modeling (horizontal)

3. Burial Grounds (vertical)

4. Central Facilities Area (CFA) (vertical)

5. Chemical Processing Plant (CPP) Pre-1963 (vertical)

6. Test Area North (TAN) (vertical)

3
FAP and Actinide (Pu, U, etc.) Intakes 

per NIOSH’s SEC ER

SEC ER Assumes:

• FAP Bioassays – Sufficient workers’ records containing 

FAP bioassay (in-vitro and in-vivo) results are available to 

assign intakes and resulting doses from FAP (some 

periods/areas may need an FAP coworker model 

developed). 

• FAP Intakes – Except for special situations, all the 

dosimetrically significant FAP intakes are directly tied to 

an indicator radionuclide (Sr-90 or Cs-137). The FAP 

ratios and intake assignment methods provided in 

ORAUT-OTIB-0054 bound all FAP exposure potentials at 

INL.

4
FAP and Actinide (Pu, U, etc.) Intakes per 

NIOSH’s SEC ER (cont’d)

SEC ER Assumes:

• Actinide Intakes – Except for special situations, the actinide 

(uranium, plutonium, thorium, etc.) intakes are directly tied 

(in a constant ratio) to the FAP; therefore, actinide intakes 

and resulting doses can be assigned using Table 5-22 (Sr-90 

ratios) and/or Table 5-23 (Cs-137 ratios) of ORAUT-TKBS0007-5 (TBD-5).

• Special Situations Actinides – Personnel involved in 

operations and situations (planned or unplanned) with 

actinides present, that were not directly tied to an FAP in a 

constant ratio, were adequately monitored, and the results 

are available in the workers’ records. Therefore, actinide 

intakes and resulting doses can be reconstructed in these 

special cases.

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SC&A’s Approaches to Evaluate 

NIOSH’s Methods

• NOCTS – Evaluate positive bioassay data in INL claimants’ files 

for radionuclide ratios

• SRDB – Evaluate documents with workers’ bioassay data for 

radionuclide ratios

• SRDB – Evaluate documents with CAM/filters/smears data for 

radionuclide ratios

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SC&A’s Current Progress

Preliminary results show:

• Some recorded data provide lower FAP intakes than would be 

assigned by using ORAUT-OTIB-0054

• Some recorded data provide lower actinide (Pu-238) intakes 

than would be derived by using ORAUT-TKBS-0007-5

• Some recorded data provide for greater actinide intakes (Pu-238 

and/or Am-241) than would be derived by using ORAUT-TKBS0007-5.

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Areas to be Addressed by SC&A

• SC&A is currently determining if the burnup in the fuel 

elements used by NIOSH is applicable/bounding to the 

situations at INL.

• SC&A is currently investigating the use of one model and only 

three fuel elements to bound the intakes/doses.

• SC&A needs to determine if records of analyses of dissolver 

contents (chopped/shredded fuel elements) are available; 

preferably, for a variety of INL reactor fuel elements.

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Areas to be Addressed by SC&A (cont’d)

• Document research is still needed to evaluate NIOSH’s 

recommended ratio value, especially for actinides. 

• Further investigations will be aided by the recent electronic 

bioassay database; even if this database is presently 

incomplete, paired FAP and actinide bioassays can provide 

relevant information.

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Reactor Modeling

• Concerns: Frequently, air-sampling or urinalysis data on worker 

exposure to mixed fission and activation products associated with 

nuclear reactors or fuel are available only in the form of gross beta or 

gross gamma activity unattributed to specific radionuclides. ORAUTOTIB-0054 provides guidance on assigning radionuclide-specific 

intakes using ratios to Cs-137 or Sr-90 indicator radionuclides. 

The OTIB considers nine cases for four representative reactors with 

different specific power levels, irradiation times, and burnups.

• Are the many INL reactors and operating scenarios (some of 

which are “exotic”) adequately enveloped by the OTIB cases so 

that the isotopic ratios are valid? 

• Have all off-normal operating scenarios been identified and are 

they adequately enveloped by the OTIB methodology? 

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Reactor Modeling (cont’d)

• Recommendations: Investigations so far have been primarily 

for normal operations of the three major Test Reactor Area (TRA) 

reactors: Materials Test Reactor (MTR), Engineering Test Reactor 

(ETR), and the Advanced Test Reactor (ATR). Investigate the 

applicability of OTIB-0054 to the:

• off-normal operating scenarios, including “special” materials 

irradiation runs and any incidents for the TRA reactors.

• characteristics of normal and off-normal operating scenarios 

of other INL reactors, such as in Test Area North (TAN), 

which hosted very unusual reactor experiments, such as the 

Advanced Nuclear Propulsion (ANP) reactors, which were 

decidedly different in fuel composition and arrangement and 

operation than other types of reactors. 

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Burial Grounds

Concerns

• Evidence exists that a “strict” contamination control 

program not in place

• Site apparently lacked adequate smear counting capability 

for some length of time before early 1970s

• Radioactive waste not specifically identified for most drums, 

boxes, and other containers in early years

• Offsite waste received from commercial, university, ERDA, 

and military sources in 1960–1963 inadequately identified 

• AEC concerned over conflicted role of health physicists at 

the Burial Grounds, who were responsible for much of its 

operation, as well as radiation protection

• Internal investigations and appraisals bring into question 

“robustness” of HP program and “defense-in-depth” 

approach for radiological controls, as cited by ER

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Burial Grounds (cont’d)

Recommendations

• Conduct additional interviews with former Burial Grounds 

workers with experience during the time period in 

question (1952–1970); emphasis on radiological control 

program

• Conduct additional data capture with focus on following:

• Additional evidence of potential intakes to radwaste handlers

• How contamination control was administered

• Available routine and special air sampling data 

• Robustness of health physics program: independence, 

resources, monitoring practices

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Burial Grounds (cont’d)

Recommendations

• Evaluate dose assessment feasibility 

• Review external and internal dose electronic database 

when completed by NIOSH

• Historic bioassay procedures and practices

• Can all Burial Ground workers be identified?

• Can all significant radioactive waste source terms be 

identified and addressed?

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Central Facilities Area (CFA)

• Concerns

• CFA-handled radioactive materials from the entire INL 

site consisting of MFP, MAP, actinides, or a mixture of 

any or all

• Difficult to bound MFP/MAP internal doses by 

assessing missed Sr-90 and/or Cs-137 intakes using 

ORAUT-OTIB-0054 and ORAUT-OTIB-0060

• Because radioactive mix is not known, not practical to 

use Sr-90 and/or Cs-137 ratios in ORAUT-TKBS-0007-5 

to determine actinide intakes

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Central Facilities Area (CFA) (cont’d)

Facilities of Concern

• CF-640 Machine Shop – Radioactive material that the plant 

shops could not handle was worked on in the more fully 

equipped CFA Machine Shop. Usually this material was of a low 

radiation and contamination level.

• CF-665 Maintenance Shop – Worked on vehicles and equipment 

that were used to haul radioactive material. Vehicles were 

surveyed prior to shop maintenance work and sent to CPP for 

decontamination if needed.

• CF-669 Central Facilities Laundry – Washed coveralls and other 

protective clothing items used at INL. The old laundry facility 

(CF-699) was used from 1950 and was demolished in 1994.

• CF-674 Sewage Treatment Plant – Small amounts of radioactivity 

were processed through CF-674 to a drying pond. Most of the 

radioactivity was from the hot laundry, although small amounts 

could enter from CF-656 (Engineering Lab) and CF-690 

(Analytical Lab).

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Central Facilities Area (CFA) (cont’d)

Recommendations

• Evaluate the CFA radiological survey and air sampling 

results, both during operations and just prior to D&D, 

to determine actinide to Sr-90 and actinide to Cs-137 

ratios.

• Compare these ratios to the values in Tables 5-22 and 

5-23 of ORAUT-TKBS-0007-5.

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Chemical Processing Plant (Pre-1963)

• Currently proposed SEC Class 1963–1974

• Rationale for SEC Class: “Increased potential for intake due 

to poor contamination control and inadequate personnel 

monitoring for exposures to transuranics separated from mixed 

fission products makes it unlikely that exposures to alpha 

emitters can adequately be reconstructed from January 1963 

through December 1974.” (NIOSH SEC ER)

• NIOSH has determined it is feasible to reconstruct all internal 

and external exposure at CPP prior to 1963

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Chemical Processing Plant (Pre-1963) 

(cont.’d)

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Chemical Processing Plant (Pre-1963) 

(cont.’d)

Concerns and Focus of SC&A Investigation

• Evaluate contamination incidents and control program 

prior to 1963

• Assess internal dosimetry program for CPP workers 

• Review of relevant claims for bioassay coverage in 

relation to established assignment to CPP

• Adequacy of bioassay program to cover internal 

exposures to alpha emitters (e.g., uranium, plutonium)

• Characterize temporal changes in source term and 

exposure potential

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Chemical Processing Plant (Pre-1963) 

(cont.’d)

Recommendations for Continued SC&A Investigative Activities 

• Site Research Database Review

• Documented contamination events and evaluation of 

contamination control program

• Variations in radiological activities (source terms) at CPP

• Hardcopy bioassay data specific to alpha emitters

• Claim File Review

• Compile internal monitoring data on randomly sampled 

claimant population at CPP

• Identify any incidents reported in dosimetry records or CATI 

reports

• Evaluate the adequacy of internal monitoring for the purpose of 

dose reconstruction

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Test Area North (TAN)

• Aircraft Nuclear Propulsion Program (ANP) (1952–1961)

• Initial Engine Test (IET)

• Heat Transfer Reactor Experiments

• Technical Support Facility (TSF)

• TAN 607 Hot Shop

• LOFT (TAN 650)

• Storage Pool

• Storage Pads (TAN 790 and 791)

• Radwaste Liquid Disposal System

• Storage Building

• Radiography Facility (TAN 607)

• Water Reactor Research Test Facility (WRRTF)

• Low Power Test Facility (LPTF)

• Shield Test Pool Facility (STPF)

• Specific Manufacturing Capability (SMC)

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TAN Scope of Analysis

• Focused on completeness of the external 

dosimetry data because:

• Our review of the Evaluation Report and Site 

Profile revealed that, with the possible exception 

of neutron data, the quality of the external 

dosimetry data was very high

• Review of the internal dosimetry data was being 

performed site-wide by others on our team and 

their findings would be applicable to TAN

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SRDB Documents Analyzed for TAN to Date

• Table 6, pp. 27–28 of Interim Report

– 37 SRDB documents with dosimetry data analyzed

– 12,177 pages in total

– Areas mentioned within documents include ANP, 

TSF, IET/STEP, STPF, LPTF, and TAN in general

– Records estimated to contain approximately 

200,000 badges in total

– Records contain approximately 7,000 neutron 

badges

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External Dosimetry – TAN as a Whole

(Data Gaps)

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Each point on this graph represents a date for which a dosimeter change-out was observed 

within the SRDB documents for a worker corresponding to any area of TAN. Numerous 

dosimeter change-out dates were seen for each year, with the exception of 1961, which had 

a small temporal gap in the available data. 
External Dosimetry – Sub-Areas of TAN

26
Preliminary Observations and 

Recommendations for TAN

• Our preliminary review of the quality and 

completeness and the external dosimetry data at TAN 

is favorable.

• There appear to be some temporal and information 

gaps, particularly for dosimeters of sub-areas of TAN, 

and additional SRDB searches may help fill these gaps. 

• Analysis of the completeness of neutron dosimetry 

data is underway.

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Preliminary Observations and 

Recommendations for TAN (cont’d)

• The external dosimetry records sometimes do not provide 

information on the sub-area where a worker experienced 

his exposures for a given change-out. In light of the highly 

varied activities that took place at the different sub-areas, 

the complete TAN dataset cannot be used to build a 

coworker model for unmonitored workers at a given facility 

within TAN. It is therefore recommended that the data 

available for each sub-area be compiled and plotted for use 

in building a coworker model for each sub-area, if it is 

determined that coworker models are needed due to the 

incompleteness of the external dosimetry database.

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